Maybe you've seen one of them. (I have.) And perhaps you thought, as I did, "This is really interesting and everything, but did these people really all donate their bodies to be sent on tour around the country? Are we sure?"

The answer, it turns out, depends on the show. The director of Body Worlds promises that every body in his exhibition comes from donors, who gave permission, in writing, for their bodies to be displayed. But you just have to trust him -- he won't provide any paperwork documenting that consent.

BODIES is a little more straightforward: Its curators make no claims that the bodies in their show were donated, only that they're "unclaimed."

For some state officials, that doesn't sit right.

Pennsylvania state Rep. Michael E. Fleck is preparing a bill that would regulate plastination exhibits, requiring written consent from the deceased or their next-of-kin clearly stating that they allow their body to be used for a profit-making enterprise.

"I'm ashamed to say this needed to be done long ago, but at least we're working on it now," Mr. Fleck said. "If we regulate taxidermy and funeral directors, we should regulate this."

Fleck's not the first state official to have qualms about these displays. Before the BODIES exhibit's U.S. debut, in Tampa, the Florida attorney general expressed doubts about the show, saying the State Anatomical Board's approval should be required. The Board fought the Tampa exhibit and tried to shut it down, but the exhibit went on anyway.